Autocollimating reflector



1933 A. GARBARINI AUTOCOLLIMATING REFLECTOR Filed Sept. 8, 1926 Patented Nov. 7, 1933 1,934,492

AUTOCOLLIIVIATING REFLECTOR Andr Garbarini, Courbevoie, France, assignor, by mesne assignments, to Libbey-Cataphote Ccporation, Toledo, Ohio, a corporation of O 'o Application September 8, 1926, Serial No. 134,204, and in France December 24, 1925 23 Claims. (Cl. as-1) y Autocollimating reflectors as actually in use In the case of a coloured reflector, the smaller are open to many objections, attributable for the hemisphere a is attached to the larger one, the most part to their construction, the restricted union being eiected by any appropriate jointing angle of field, the necessity of orientation, fragilmaterial, such for instance as Canada balsam,

5 ity, the necessity of great care to preserve air Venetian cement or the like. 60 tightness, so as to prevent the production of Inpractice the two hemispheres may be roughly mistiness or of a film on the interior, and finally moulded as regards the spherical portion, the attributable to the destructible character of the plane portions alone being polished for accurate metallic parts. tting.

w The present 'invention relates to an improved The fitting may be effected more easily by 35 autocollimating reflector of eminently simple conadopting the arrangemen-t illustrated at Fig. 2,, struction, obviating the before mentioned drawin which the larger hemisphere b is provided k with a bevelled portion b which facilitates cen- According to the general principle of the intering Or dl s ent, vention two glass hemispheres or spherical seg- The ratio of the radii r and R is a function of 79 ments of different radii are united together in the index of refraction of the constituent matea plane Which is diametric or substantially diarials of the hemispheres as well as of the divermetric. The relation of the radii is a function gence which is desired.

of the index o refraction of the constituent ma- The divergences are obtained by separating the terial, and with reference to the desired amount centres, so that the centre of the spherical seg- 7 of divergence. menta comes on the exterior, as shown at Fig. 3

It is found that this arrangement gives a very or on the interior of the hemisphere b, as shown large angle of field, up to 160". The front at Fig. 4. hemisphere may be white or coloured. The back Accordingly, by locating the refiector between hemisphere is covered on the outside with'a coatthe center of curvature and the vertex of the 80 ing of silver or of gilt. optical lens, as indicated in Fig. 4 of the draw- The divergenceis obtained, in one direction or ing, the exact relation of these centers to be in the other by separa-ting the centres of the determined by the index of refraction of the hemispheres, so that the centre of the small front particular glass used and by the divergence de- 39 hemisphere comes at the outside or beyond, or sired in a given instance, the central ray of any 85 on the interior with respect to the rear hemibundle of light rays impinging on the objective sphere. lens will impinge upon the refiector along a sub- The annexed drawing shows, by way of exam stantially radial line and the extra-axial rays of ple, varlous constructional embodiments of auto the incident bundle will be substantially collimating refiectors constructed according to metrically reflected so as to emerge substantially o the invention, and also two' examples of their ap- Symmetrca y On t side Of the a a Y pp plication. site to that of their incidence.

F 1 i a ide 1 v ,ti of a ui t m A multicoloured autocollimating refiector may trating the principles of the n i n be utilized as a direction signal,-as shown at Fig. v 40 Figs. 2, 3 and 4 are side eleva-tions of various Wth this arrangement, according as one can 95 tru ti l embodiments, see from the car to be directed, one or other of Fg 5 is front elevation of a t m the outer bancls c or 0 it is indicaied that one limator for indicating direction. is to the right or left of the line to be followed.

Fig. 6 is a front elevation of a board for indi- The portions 01 and 02 y be ven either the cating distances. same colour or preferably different colours. 100

As will be seen from 'the drawing, the auto- The arrangement just described is particularly collimating reflector is formed by joining together suitable for ships to give pilots the direction to two hemispheres or substantially hemispherical follow, for instance When entering ports, chanportions, a front element a and a rear element b, nels, passages marked out by buoys, when passof respective curvatures r and R.. ing between the piles of bridges, and so on. 105 The small hemisphere a is white or coloured or The white portion which is advantageously proof two colours. The hemisphere bis covered on vided between the coloured sections indicates the the outside b with a silvered or gilt coating. true direction or alignment. The two hemispheres may be cast together in the For indicating distances from a fixed point, case of a white refiector. as for instance distances from a stopping place llO ersed to reach the aerodrome.

The numeral 3 is made up from the autocollimators e of slight divergence. The numeral 2 is made up from the autocollimators f o! greater divergence, whilst the numeral' 1 is made up from the autocollimators b of still greater divergence than these last mentioned, such divergences being determined on the one hand by the distance A of necessary visibility, and on the other hand by the distance of the eye from the luminous sourcea distance calculated perpendicular to the axis of visibility. 4

It will be understood that when an aeroplane arrives opposite 'the irame, the pilot will immediately be informed as to the distance separating him therefrom, and this will permit him to carry out the necessary manaeuvres as to direction and landing at the proper moments.

The device will also be of great interest for trains or locomotives, to indicate to the engineer the distance of the signals, points, sidings or cross-overs or the like.

The system may also be applied for publicity purposes, the numerals being replaced by letters r or words.

What I claim and desire to secure by Letters Patent of the United States is:--

1. An autocollimating reflector comprising a substantially hemispherical rear lens, having a 'refiecting coating on its spherical surface, and a smaller hemispherical lens cemented to the plane race oi' the larger lens, the center of curvature of the smaller lens being positioned away from the center of 'the larger lens in accordance With the desired divergence of the reflected light and the larger lens having a conical surface from the margn of the plane face of the smaller lens to the periphery of the larger lens.

2. An autocollimating reflector comprising a lens portion having a substantially hemispherical rear face, a reflecting coating thereon and a smaller substantially spherical hemispherical lens portion, the 'centers of curvature of the two lens portions being non-coincident in accordance with the desireddivergence of the refiected light and a conical portion connecting the curved portions of the two lenses.

lens portion having a curved face, a reflecting coating on' said face, a smaller lens portion having a curved face, the centers of curvature of the two faces being non-coincident in accordance with the desired divergence 'of the 'reflected light and a conical portion connecting the other two portions.

4. An autocollimating reflector comprising a glass having a small spherical suri'ace at one end, a large spherical surface at the other end said surfaces having different radii of curvature, a conical portion connecting the surfaces and a reflecting coating on the large 'spherical surface.

5. An autocollimating reflector comprising a lens portion having a substantially hemispherical rear face, a reflector thereon, and a smaller substantially hemispherical lens portion, the-centres of curvature of the two lens portions being nonco-incident-in accordance with the desired di- 3. An autocollimating reflector. comprising a vergence of the reflected light, and a conical portion connecting the curved portions of the two lenses.

i 6. An autocollimating reflector', comprising a lens portion having a curved face, a reflector on said face, a smaller lens portion having a curved race, the centres of curvature of the two taces being non-coincident in accordance with the desired divergence of the reflected light, and a conical portion connecting the two portions.

7. In combination, a plurality of sets of autocollimating refiectors, the reflectors of each set having a different angle of divergence from those of another set.

8. In combination, a. plurality of sets of autocollimating refiectors the reflectors of one set having diflerent divergence from those of another set, whereby when light is directed on the combination the sets will be successively visible as the source of light approaches.

9. In combination, a plurality of sets of autocollimating refiectors, each reflector comprising a spherical lens at one end and a spherical reflecting surface at the other end the distance between the centers of curvature of *the lenses and reflectors diiering in the diierent sets.

10. An optical unit of the reflecting type comprising a glass body having its ends convexly spherical and having its rear end reflective, the center of curvature oi the rear face being so positioned for the particular index oi refraction of the glass and the radius of the rear facebeing such that the central or axial ray of an oblique'bundle of incident rays of light will pass substantially through said center and the extra-axial rays of no the incident bundle will. be substantially symmetrically reflected so as to emerge symmetrically on the side of the axial ray opposite to that of their incidence.

11. An optical unit of the reflecting type comprising a glass body having its ends canvexly spherical and having its rear end refiective, the center of curvature of therear face being so positioned for the particular index of refraction oi the glass and the radius of the rear' face being such that the central or axial ray of an oblique bundle of incident rays of light will pass substantially through said center and the extra-axial rays of the incident bundle will be substantially symmetrically reflected as a diverging cone of light the axis oi which is substantially parallel to the direction of incidence.

12. An optical unit of the reflecting type comprising a lens and a concave reflector at the rear end of the lens, the center of curvature of the reflector being so located in advance of the center of curvature of the lens that for a given index of refraction of the material of the lens the central ray of an incident bundle of rays of light either parallel to the axis or oblique to the axis of the lens will strike the reflector along substantially a radial line, and the length of the radius of the reflector exceeding that oi the fro'nt face of the lens and proportioned thereto so that the extra axial rays of the incident bundle will be substantially symmetrically reflected so as to emerge symmetrically on the side of the axial ray opposite to that of their incidence.

13. An optical unit oi the reflecting type comprising a lens and a concave reflector behind the lens disposed with its vertex substantially at the tocal point of a bundle oi rays axially incident upon the lens and having its center of curvature on the axis o! the system substantially at the point where the axis' is'intersected by the line of 150 incidence upon the refiector of the' central ray of a bundle of rays obliquely incident upon the objective face of the lens.

14. An autocollimating refiector comprising a hemispherical objective lens and a hemispherical refiector having a longer radius than the objective lens, a light reflecting coating on the outer surface of the refiector, the objective and refiector being joined along their diametrical plane, the Structure being tapered from the margin of the refiector to the margin of the objective, the objective and the refiector being so arranged upon the same optical axis that the centers of their respective radii of curvature are not coincident.

15. An autocollimating refiector comprising a colored, hemispherical le'ns'united with a hemispherical refiector of larger radius than the lens, the refiector having a light refiecting coating, the objective and reflector'being arranged on a common optical axis, the respective centers of curvature of the objective and the refiector being non-coincident, the structure tapering between the margin of the refiector and the margin of the objective.

16. An autocollimating refiector comprising a single piece of glass .formed with an objective lens at one end, a reflecting lens of larger diameter than the objective at the other end and provided with arefiecting surface on its periphery, and a tapered portion between. the objective and refiecting lenses.

17. An autocollimating refiector emprising a' glass unit formed with an objective 'lens at one end, a spherical surface at its other end of larger radius than the radius of the objective' lens, a, tapered surface between* its ends, the larger spherical surface being provided with a refiecting surface on its periphery.

19. A glass unit comprising an'objective lens and a concave refiector arranged on the same optical axis, the refiector having a greater radius than the objective, the respective centers of the curvature of the objective and refiector being non-coincident, the refiector extending beyond the margin of the objective, and an unobstructed light transmitting portion between the margins of the objective and the refiector.

20. An autocollimating refiector comprising a glass unit formed to provide an objective lens at one end, a refiector at the other end having a larger radius of urvature than the objective, a tapered por tion between the objective 'and the refiector, and having a refiecting coating on the refiector.

21. An autocollimating refiector comprising a lens portion provided with a reflecting surface, an oppositely arranged objective lens portion having a smaller radius of curvature than the first named lens, the centers of curvature of the two faces being non-coincident in. accordance with the desired divergence of the refiected light, and a tapered portion betweenthe objective and the refiector.

22. An 'auto'collimating refiector comprising a hemispherical objective lens and a, hemispherical refiector having a longer radius than the objectivejlens, a light reflecting coating on the outer surface of the refiector, the objective and refiector being joined by a tapered body portion extending from the margin of the refiector to the margin of the objective.

23. An optical unit of the refiecting type comprising a glass body provided at one end with an objective lens and having its rear end reflective, the center of curvature of the rear face being so positioned for the particular index of refraction of the glass, and the radius'of the rear face being such that the central or axial ray of an oblique bundle of incident r'ays of light will pass substantially through said center. and the extra axial rays of the incident'bundle will be substantially symmetrically refiected so as to emerge symmetrically on the side of the axial ray opposite to that of their incidence.

ANDR GARBARII. 

